Field of the Invention
The present invention relates to an interchangeable lens and particularly to a power saving technique for the interchangeable lens including an external display.
Description of the Related Art
Image capturing apparatuses, such as digital cameras, have a power saving function of transitioning to a low power consumption state (power saving mode) when no operation has been performed by a user in a normal operation state for a predetermined time period. In image capturing systems including a lens-interchangeable image capturing apparatus and an interchangeable lens, when the image capturing apparatus transitions to the low power consumption state, the image capturing apparatus sends, to the interchangeable lens, a transition instruction to instruct a transition to the low power consumption state. Upon receipt of the transition instruction, the interchangeable lens transitions from the normal operation state to the low power consumption state. For instance, when the interchangeable lens includes an external display (hereinafter referred to as “a lens external display”) that displays information on the image capturing system, the interchangeable lens transitions, in its transition to the low power consumption state, the lens external display from a display state to a non-display state.
As a power saving method in the image capturing apparatus, Japanese Patent Laid-Open No. 2000-19618 discloses a method that, when the image capturing apparatus including the external display is in a normal position that allows the user to easily view the external display, sets a period of time for which illumination of the external display is continued.
The above-described transition of the lens external display from the display state to the non-display state approximately simultaneous with the transition of the image capturing apparatus to the low power consumption state prevents the user checking the above-described information on the lens external display without operating the image capturing apparatus from viewing the information. In order to view the information again on the lens external display, the user is required to perform an operation of some kind on the interchangeable lens or the image capturing apparatus to return the interchangeable lens or the entire image capturing system to its normal operation state. This requirement of frequently performing the above-described return operation for the transition to the normal operation state due to the transition of the lens external display to the non-display state decreases usability of the image capturing system.